dingusppc/devices/viacuda.h

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//DingusPPC - Prototype 5bf2
//Written by divingkatae
//(c)2018-20 (theweirdo)
//Please ask for permission
//if you want to distribute this.
//(divingkatae#1017 on Discord)
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/** VIA-CUDA combo device emulation.
Author: Max Poliakovski 2019
Versatile interface adapter (VIA) is an old I/O controller that can be found
in nearly every Macintosh computer. In the 68k era, VIA was used to control
various peripherial devices. In a Power Macintosh, its function is limited
to the I/O interface for the Cuda MCU. I therefore decided to put VIA
emulation code here.
Cuda MCU is a multipurpose IC built around a custom version of the Motorola
MC68HC05 microcontroller. It provides several functions including:
- Apple Desktop Bus (ADB) master
- I2C bus master
- Realtime clock (RTC)
- parameter RAM (first generation of the Power Macintosh)
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- power management
MC68HC05 doesn't provide any dedicated hardware for serial communication
protocols. All signals required for ADB and I2C will be generated by Cuda
firmware using bit banging (https://en.wikipedia.org/wiki/Bit_banging).
*/
#ifndef VIACUDA_H
#define VIACUDA_H
/** VIA register offsets. */
enum {
VIA_B = 0x00, /* input/output register B */
VIA_A = 0x01, /* input/output register A */
VIA_DIRB = 0x02, /* direction B */
VIA_DIRA = 0x03, /* direction A */
VIA_T1CL = 0x04, /* low-order timer 1 counter */
VIA_T1CH = 0x05, /* high-order timer 1 counter */
VIA_T1LL = 0x06, /* low-order timer 1 latches */
VIA_T1LH = 0x07, /* high-order timer 1 latches */
VIA_T2CL = 0x08, /* low-order timer 2 latches */
VIA_T2CH = 0x09, /* high-order timer 2 counter */
VIA_SR = 0x0A, /* shift register */
VIA_ACR = 0x0B, /* auxiliary control register */
VIA_PCR = 0x0C, /* periheral control register */
VIA_IFR = 0x0D, /* interrupt flag register */
VIA_IER = 0x0E, /* interrupt enable register */
VIA_ANH = 0x0F, /* input/output register A, no handshake */
};
/** Cuda communication signals. */
enum {
CUDA_TIP = 0x20, /* transaction in progress: 0 - true, 1 - false */
CUDA_BYTEACK = 0x10, /* byte acknowledge: 0 - true, 1 - false */
CUDA_TREQ = 0x08 /* Cuda requests transaction from host */
};
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/** Cuda packet types. */
enum {
CUDA_PKT_ADB = 0,
CUDA_PKT_PSEUDO = 1,
CUDA_PKT_ERROR = 2,
CUDA_PKT_TICK = 3,
CUDA_PKT_POWER = 4
};
/** Cuda pseudo commands. */
enum {
CUDA_READ_WRITE_I2C = 0x22, /* read/write I2C device */
CUDA_COMB_FMT_I2C = 0x25, /* combined format I2C transaction */
CUDA_OUT_PB0 = 0x26, /* output one bit to Cuda's PB0 line */
};
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/** Cuda error codes. */
enum {
CUDA_ERR_BAD_CMD = 2, /* invalid pseudo command */
CUDA_ERR_I2C = 5 /* invalid I2C data or no acknowledge */
};
class ViaCuda
{
public:
ViaCuda();
~ViaCuda() = default;
uint8_t read(int reg);
void write(int reg, uint8_t value);
private:
uint8_t via_regs[16]; /* VIA virtual registers */
/* Cuda state. */
uint8_t old_tip;
uint8_t old_byteack;
uint8_t treq;
uint8_t in_buf[16];
int32_t in_count;
uint8_t out_buf[16];
int32_t out_count;
int32_t out_pos;
void print_enabled_ints(); /* print enabled VIA interrupts and their sources */
void cuda_init();
bool cuda_ready();
void assert_sr_int();
void cuda_write(uint8_t new_state);
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void cuda_response_header(uint32_t pkt_type, uint32_t pkt_flag);
void cuda_error_response(uint32_t error);
void cuda_process_packet();
void cuda_pseudo_command(int cmd, int data_count);
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/* I2C related methods */
void i2c_simple_transaction(uint8_t dev_addr, const uint8_t *in_buf, int in_bytes);
void i2c_comb_transaction(uint8_t dev_addr, uint8_t sub_addr, uint8_t dev_addr1,
const uint8_t *in_buf, int in_bytes);
};
#endif /* VIACUDA_H */